[C:1]([O-:4])(=[O:3])[CH3:2].[K+].C(O)(=O)C.Cl[CH2:11][C:12](=[O:18])[CH2:13][C:14]([O:16][CH3:17])=[O:15]>[Cl-].C([N+](CC)(CC)CC)C1C=CC=CC=1.C(#N)C>[C:1]([O:4][CH2:11][C:12](=[O:18])[CH2:13][C:14]([O:16][CH3:17])=[O:15])(=[O:3])[CH3:2]108 g (1.1 mol) of potassium acetate and 11.4 g (0.05 mol) of benzyltriethylammonium chloride are suspended in 900 ml of acetonitrile, treated with 50 ml of acetic acid and heated to reflux temperature. Within 31/2 hours there are added dropwise thereto 150.5 g (1 mol) of methyl 4-chloroacetoacetate in 100 ml of acetonitrile and the mixture is subsequently held at reflux temperature for 4 hours. The reaction mixture is washed 3 times with 200 ml of 5% NaH2PO4 solution each time and the aqueous phases are back-extracted with 200 ml of CH2Cl2. The combined organic phases are dried over magnesium sulphate and concentrated on a rotary evaporator. The crude product distils at 76°-85° C./0.6 mbar and gives 106.17 g (61%) of methyl 4-acetoxyacetoacetate.
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